Saturday, 31 October 2015

TheBritish Geological Surveyrecorded a Magnitude 1.4 Earthquake at a depth of about 2 km about 5 km to the south of the town of Peebles in Borders Region of Scotland, slightly after 12.30 pm GMT on Sunday 25 October 2015. This was not a major event, and presented no threat to human life or property, but may have been felt locally.

The approximate location of the 25 October 2015 Peebles Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone to quakes than the rest of Wales or most of England.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process.

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

Asteroid 1998 XN2 passed by the Earth at a distance of 11 610 000 km (30.2 times the average distance between the Earth and the Moon, or 7.76% of the average distance between the Earth and the Sun), slightly before 2.55 pm GMT on Sunday 25 October 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented a considerable threat. 1998 XN2 has an estimated equivalent diameter of 230-710 m (i.e. it is estimated that a spherical object with the same volume would be 230-710 m in diameter), and an object of this size would pass through the atmosphere and directly impact the ground with a force of about 400-1600 megatons (roughly 23 500 to 94 000 times the explosive energy of the Hiroshima bomb), causing devastation over a wide area and creating a crater about 3.5-12 kilometers across, and resulting in global climatic problems that could last for decades or even centuries.

1998 XN2 has a 1033 day orbital period and an eccentric orbit tilted at an angle of 1.78° to the plane of the Solar System, which takes it from 0.92 AU from the Sun (i.e. 92% of the average distance at which the Earth orbits the Sun) to 3.08 AU from the Sun (i.e. 308% of the average distance at which the Earth orbits the Sun, slightly outside twice the orbit of Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that close encounters between the asteroid and Earth are extremely common, with the last having occurred in December 1998 and the next predicted in August 2032. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 1998 XN2 is also classified as a Potentially Hazardous Asteroid.

Asteroid (445830) 2012 CL19 passed by the Earth at a distance of 6 687 000 km (17.4 times the average distance between the Earth and the Moon, or 4.47% of the average distance between the Earth and the...

Asteroid (385186) 1994 AW1 passed by the Earth at a distance of 9 725 000 km (25.3 times the average distance between the Earth and the Moon, or 6.50% of the average distance between the Earth and the...

Asteroid (1566) 1949 MA Icarus passed by the Earth at a distance of 8 054 000 km (20.9 times the average distance between the Earth and the Moon, or 5.38 % of the average distance between the Earth and the...

Dromaeosaurids were first
described in the 1920s, but received relatively little attention from
palaeontologists until the late 1960s. However in recent years it has been
realized that the group were the closest non-avian relatives of the Birds, and
they have become one of the best studied of all Dinosaur groups. The majority
of Dromaeosaurids were small animals with wing-like forelimbs and feathers,
interpreted as having lived much of their lives in the treetops, with some
species thought to have been capable of true flight and others of gliding.
However other members of the group retain feathered wings despite being clearly
quite incapable of flying due to their size and shape, leading to speculation
that the ‘wings’ may have had some other purpose, quite unrelated to flight.

Among these clearly non-flying
Dromaeosaurids are four previously described ‘giant’ species, all from the Late
Cretaceous, Deinonychus antirrhopus
and Utahraptor ostrommaysi from North
America, Achillobator giganticus from
Asia and Austroraptor cabazai from
South America. Rather than forming a distinct group these giant Dromaeosaurids
appear to have arisen at least three times from more average-sized members of
the group, suggesting that some factor favoured the evolution of larger
Dromaeosaurids towards the end of the Cretaceous.

The new species is named Dakotaraptor steini, where ‘Dakotaraptor’ refers to the state where
the species was discovered and the Dakota people that gave it its name
(‘raptor’ means ‘plunderer’ in Latin and is a common suffix for Dromaeosaurids,
as well as being used as a collective name for modern Birds of Prey), and ‘steini’ honours palaeontologist Walter Stein.
The species is described from an adult specimen comprising the right pedal
unguals II & III, the right femur, the left and right tibiae, the left
astragalus and calcaneum, the left metatarsals II-IV, the right metatarsal IV,
one fragmentary dorsal centrum, 10 caudal vertebrae, the furcula, the left and
right humeri, the left and right radii, the left and right ulnae, the right
metacarpals I and II and three fragmentary left manual phalanges, plus an
isolated left tibia, a left astragalus and calcaneum, two furcula and several
teeth.

Quary map indicating the spatial relationship of the bones of the first
Dakotaraptor specimen as they were
found in the field. DePalma et al.
(2015).

The ulna of Dakotaraptor shows a row of 10 oblong protuberances, interpreted as
being quill knobs, or ulnar papilli; attachment points for flight feathers.
These have been detected before in Theropod Dinosaurs, particularly Dromaeosaurids,
as well as being known in modern and Mesozoic Birds. Importantly, in modern
Birds, these structures only develop in species that place exceptional stresses
on the wing feathers during flight. Since the size and shape of Dakotaraptor makes it highly unlikely
that it was capable of any form of flight, it seems likely that it was placing
stress on its wing feathers engaging in some other form of activity. This has
been seen previously in other Dromaeosaurids deemed unlikely fliers (for
example Velociraptor) and has led to
a number of suggestions as to possible uses for wing feathers in
Dromaeosaurids, such as brooding eggs and young or subduing prey. DePalma et al. feel that the brooding young
explanation cannot explain the deep ulnar papilli seen in Dakotaraptor and other Dromaeosaurids, and therefore reject this
hypothesis, but do feel they lend to support to the idea that strong feathers
may have aided prey suppression in these animals.

Reconstructed Dakotaraptor
wing and plumage, with Avian and Theropod comparisons. (A) Enlarged view of the
quill knobs on the Dakotaraptor ulna,
compared with quill knobs in Velociraptor
(B) and Concavenator (C); (D) conservative
reconstruction of the wing plumage for Dakotaraptor
based on quill knob placement and comparison with other Dromaeosaurid and Bird wings;
(E) quill knobs on a modern Masked Booby (Sula
dactylatra) ulna, and (F), X-ray of a modern Barred Owl (Strix varia) wing showing attachment of
the remiges on the quill knobs. The flattened dorsal surface of Dakotaraptor’s metacarpal II would have
provided a stable shelf for the primary remiges that laid across it, a possible
driving force for evolving the flat surface. Photograph (F) provided by Smalley’s Animal Hospital. DePalma et al.
(2015).

Dakotaraptor is interpreted as being exceptionally large for a
Dromaeosaurid, or indeed any form of Maniraptoran (the group of Theropod
Dinosaurs that includes Dromaeosaurids and Birds, as well as other group such
as Troodontids), reaching about 5.5 m in length and exceeding in size all other known Dromaeosaurids accept Utahraptor, which was similar in size
and to which it is interpreted as being closely related. However while Utahraptor is interpreted as being a
slow moving animal with a distinct morphology, Dakotaraptor appears to be essentially a scaled up version of the
smaller Dromaeosaurids, and like them is thought likely to have been a highly
active predator (though unlike them it is not thought to have been capable of
any form of flight, as in larger flying animals the wing must be scaled up
relative to the rest of the body, while Dakotaraptor
retains its proportions).

Skeletal reconstruction of the most intact Dakotaraptor
specimen based on available material for Utahraptor,
Dromaeosaurus, Deinonychus, and Achillobator,
demonstrating overall proportions and the large size of the creature. Preserved
elements shown in insert. DePalma et al.
(2015).

As such Dakotaraptor presents a significant expansion of the known Hell
Creek fauna, which previously, as well as a range of herbivorous Dinosaurs,
included small Dromaeosaurid and large Tyranosaurid pedators, but no carnivores
of intermediate size, something that would be expected in a similar modern
fauna. DePalma et al. also note that
the discovered specimens of Dakotaraptor,
which are all interpreted as being adults group into two morphologies, a more
robust form and a more gracile (slender) form. These specimens could represent
variations within a population, but DePalma et
al. feel that it is unlikely that only the more extreme variations would be
preserved with no intermediate specimens, and therefore suggest that the two
morphotypes may represent a sexually dimorphic species (species in which one
sex is notably more robust than the other). They further note that this
interpretation fits with the often-made suggestion that Dromaeosaurids may have
been pack hunters, living permanently in some form of family group.

Interpretation of Dakotaraptor as
a living animal. Emily Willoughby in DePalma et al. (2015).

Dromaeosaurid Dinosaurs are among the closest non-Avian relatives of the Birds and show many similarities to the earliest members of that group, making understanding Dromaeosaurs important for understanding the origin of Birds. In particulary...

The Dromaeosaurs were a group of small, feathered dinosaurs closely related to the birds. They are commonly referred to as 'raptors' on account of an enlarged claw on each foot which was held clear of...

Two homes in the town of Seffner in Hillsborough County, Florida, have been evacuated after a sinkhole appeared between them on Friday 30 October 2015. The hole measures 6.7 m across and is estimated to be 8 m deep. Nobody was injured in the incident, and the homes have been evacuated purely as a precaution while the hole is investigated.

Sinkhole which appeared between two homes in Seffner, Florida on 30 October 2015. WFTS.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.

The approximate location of the 30 October 2015 Seffner sinkhole. Google Maps.

Southwest Florida is particularly prone to sinkholes, due to the porous limestone that underlies much of the area. This is eroded over time by acid in rainwater (most rainwater is slightly acidic, though pollution can make this worse), and can collapse suddenly, causing overlying sediments to collapse into the hole and a sinkhole to open up. This can be triggered by human activity, such as pumping water out (which causes the water to flow, facilitating acid dissolution of the limestone), but is essentially a natural process.

Two homes have been destroyed and a further four evacuated after a sinkhole opened up in Dunedin in Pinellas County, Florida on Thursday 14 November 2013. The hole first appeared early in the morning...

A three story holiday villa at a resort in Lake County, Florida, has partially collapsed into a sinkhole described as between 12 and 15 meters wide. The 24 unit building at the Summer Bay Resort in Clermont, roughly 16 km to the west of Disney World, was evacuated at about 11.30 pm local time on Sunday 11 August...

Around 11.00 pm local time on Thursday 27 February 2013, the family of Florida man Jeff Bush heard a loud crash followed by screaming from his bedroom, in Faithway Drive, Seffner near Tampa. His brother, Jeremy, rushed into the room to find the a...

Friday, 30 October 2015

The Servicio Nacional de Geología y Minería reported a small eruption on Mount Lascar, an active volcano in the northern Chilean Andes in the Antofagasta Region of Chile, occurring slightly after 9.30 am on Friday 30 October 2015. The eruption produced a plume which rose about 2.5 km above the summit of the volcano (which is 5592 m above sea-level) and drifted to the northeast. This is the first eruption on Mount Lascar since November 2013.

Lascar comprises a group of six overlapping craters on a site that has been active since at least the Late Pleistocene. The largest eruption at the site is thought to have occurred about 26 500 years ago. Most modern eruptions are comparatively small, though an eruption in 1993 caused a pyroclastic flow that reached 8.5 km from the caldera and ashfalls in Buenos Aires.

Like other volcanoes in the Andes, Lascar is fed by the subduction of the Nazca Plate beneath the South American Place along the west coast of the continent. As the Nazca Plate sinks into the Earth it passes under South America, and at the same time is partially melted by the heat and pressure of the planet's interior. More volatile elements in the melted magma to rise up through the overlying South American Plate, fueling the volcanoes of the Andes.

The Buenos Aires Volcanic Ash Advisory Center reported plume over Mount Copahue, an active volcano on the border between Chile and Argentina roughly 500 km to the south of the Chilean capitol Santiago, on Sunday 11 October 2015. The plume rose 6.1-7.6 km over the volcano, and drifted to...

Authorities in Chile have began to evacuate homes within 20 km of Mount Calbuco, a volcano in the Los Lagos Region in the south of the country, after the volcano began to erupt at about 6.00 pm local time...

TheBritish Geological Surveyrecorded a Magnitude 1.4 Earthquake at a depth of 10 km about 10 km to the west of the city of Stoke-on-Trent in Staffordshore, slightly before 7.20 am GMT on Sunday 24 October 2015. There are no reports of any damage or injuries associated with this event, and nor would they be expected from such a small event, though it is possible it was felt locally.

The approximate location of the 24 October 2015 Staffordshire Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone to quakes than the rest of Wales or most of England. However, while quakes in southern England are less frequent, they are often larger than events in the north, as tectonic presures tend to build up for longer periods of time between events, so that when they occur more pressure is released.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process.

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

About Me

Studied Palaeobiology & Evolution at the University of Portsmouth, Geosciences via the Open University & Ecology and Conservation at Christchurch University, Canterbury.
Have worked in wildlife based tourism, mineral exploration, development, conservation, education & environmental chemistry. Occasionally write articles for papers and magazines.

This Blog would be impossible without the work of countless scientists (and others) throughout the world. Where possible I do my best to credit them, but there will always be many more who remain unmentioned; this does not imply I am ungrateful for their contributions. Any errors or inaccuracies are, of course, my own.